Many power transmissions employ stationary torque-transmitting mechanisms, commonly termed brakes or reaction clutches in which the hydraulic apply piston is slidably engaged within a cavity formed in the transmission case. In some instances, the piston is slidably disposed in the transmission case and cooperates therewith to form an apply cavity or chamber. In these designs, the piston is accompanied with a seal member, which sealingly engages the transmission case, and the case is supplied with a seal member, which engages sealingly with a diameter formed on the piston. In such arrangements, it is necessary to machine finish both the case and the piston since the sealing surface must be smooth and relatively or substantially free of tool marks, which cause excess seal wear.